U.S. patent number 6,930,891 [Application Number 09/658,198] was granted by the patent office on 2005-08-16 for electromagnetic shielding plate, electromagnetic shielding structure, and entertainment system.
This patent grant is currently assigned to Sony Computer Entertainment Inc.. Invention is credited to Toshikatsu Hama, Osamu Murasawa.
United States Patent |
6,930,891 |
Hama , et al. |
August 16, 2005 |
Electromagnetic shielding plate, electromagnetic shielding
structure, and entertainment system
Abstract
An electromagnetic shielding plate having high shielding effect
is provided. The electromagnetic shielding plate is formed of a
conductive plate having elasticity and is provided on the edge
thereof with a connecting strip bent in such a manner that the tip
thereof projects from the surface of the plate, and with a
supporting portion. When the electromagnetic shielding plate and
the printed substrate are connected, it is ensured that the ground
pattern 201 of the printed board 200 and the connecting strip are
brought into contact with respect to each other, thereby a high
shielding effect can be obtained.
Inventors: |
Hama; Toshikatsu (Tokyo,
JP), Murasawa; Osamu (Tokyo, JP) |
Assignee: |
Sony Computer Entertainment
Inc. (Toyko, JP)
|
Family
ID: |
17311167 |
Appl.
No.: |
09/658,198 |
Filed: |
September 8, 2000 |
Foreign Application Priority Data
|
|
|
|
|
Sep 10, 1999 [JP] |
|
|
11-257791 |
|
Current U.S.
Class: |
361/800; 174/359;
174/51; 361/753 |
Current CPC
Class: |
H05K
9/0039 (20130101); H05K 9/0026 (20130101) |
Current International
Class: |
H05K
9/00 (20060101); H05K 007/18 () |
Field of
Search: |
;361/800,816-818,736,737,752,753,799 ;174/35R,51 ;439/607-610 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0 755 177 |
|
Jan 1997 |
|
EP |
|
63-10597 |
|
Jan 1988 |
|
JP |
|
63-153598 |
|
Oct 1988 |
|
JP |
|
6-72296 |
|
Oct 1994 |
|
JP |
|
9-186481 |
|
Jul 1997 |
|
JP |
|
10-41668 |
|
Feb 1998 |
|
JP |
|
11-30961 |
|
Feb 1999 |
|
JP |
|
85207472 |
|
May 1985 |
|
TW |
|
305518 |
|
May 1997 |
|
TW |
|
WO 94/27421 |
|
Nov 1994 |
|
WO |
|
Primary Examiner: Cuneo; Kamand
Assistant Examiner: Phan; Thanh S.
Attorney, Agent or Firm: Katten Muchin Zavis Rosenman
Claims
What is claimed is:
1. An electromagnetic shielding plate for shielding electromagnetic
radiation by covering at least a part of an object comprising: a
conductive covering plate having an edge and a plate surface; a
plurality of conductive connecting strips provided along the edge
of said covering plate, said connecting strips extending along said
plate surface and downwardly from said edge and terminating in tip
portions that conduct electromagnetic radiation from said
conductive covering plate to a ground of said object; wherein each
of said connecting strips has a front surface and a back surface in
a shape of a plate, and an edge of the front surface and an edge of
the back surface in said tip portion side are formed in a shape of
an arc in approximate point contact with said ground.
2. An electromagnetic shielding plate according to claim 1, further
comprising a supporting portion for establishing a space of a
predetermined width between said conductive covering plate and said
object, and said supporting portion being the same height as the
predetermined width from said conductive covering plate, wherein a
height of said connecting strips from said conductive covering
plate to said tip portions is higher than a height of said
supporting portion.
3. An electromagnetic shielding plate according to claim 2, wherein
said supporting portion comprises a connecting portion for
connecting said electromagnetic shielding plate with said
object.
4. An electromagnetic shielding plate according to claim 3, wherein
said covering plate and said connecting strip are integrally
formed.
5. An electromagnetic shielding plate according to claim 2, wherein
respective gaps between the plurality of connecting strips are
smaller than said predetermined width.
6. An electromagnetic shielding plate according to claim 1, wherein
said conductive covering plate includes a cabinet-fixing portion
for securing a cabinet to said plate surface.
7. An electromagnetic shielding plate according to claim 1, wherein
said plurality of connecting strips includes a first group of
connecting strips, the tips of which are bent in a first direction
relative to said plate surface, and a second group of connecting
strips, the tips of which are bent in a second direction relative
to said plate surface and opposite of said first direction.
8. An electromagnetic shielding plate according to claim 7, wherein
said covering plate is provided with a first supporting portion
extending in said first direction and a second supporting portion
extending in said second direction for establishing a space between
said electromagnetic shielding plate and a first and a second
object positioned in said first and second directions relative to
said electromagnetic shielding plate.
9. An electromagnetic shielding plate according to claim 8, wherein
said first and second supporting portions each comprise a
connecting portion for connecting said electromagnetic shielding
plate with said first and second objects.
10. An electromagnetic shielding plate according to claim 9,
wherein said connecting strips project a greater distance away from
said covering plate than said supporting portions.
11. An electromagnetic shielding plate according to claim 10,
wherein said covering plate and said connecting strips are
integrally formed.
12. An electromagnetic shielding plate according to claim 8,
wherein said connecting strips project a greater distance away from
said covering plate than said supporting portions.
13. An electromagnetic shielding plate for shielding
electromagnetic radiation by covering at least a part of an object
the electromagnetic shielding plate comprising: a conductive
box-shaped structure having a plate portion and a side surface
portion provided around the plate portion and formed integrally
therewith, the plate portion and the side surface portion lying in
transverse planes relative to each other and forming a first edge,
the side surface portion having a second edge distal from the first
edge, the side surface portion and the second edge lying in
transverse planes relative to each other; a plurality of
spaced-apart notches formed in the plate portion and the side
surface portion and defining a plurality of projections being
provided at a plurality of locations along the first edge of the
side surface portion, each of the plurality of projections
comprising a first portion extending in the plane of the plate
surface and a second portion extending in the plane of the side
surface portion, the second portion terminating at the second edge,
wherein at least one of the plurality of projections terminates in
a tip portion that conducts electromagnetic radiation from the
conductive covering plate to ground of the object, the second
portion of each of the plurality of projections having a tip shape
and being dimensioned to press against the at least part of the
object upon covering the at least part of the object of the
conductive covering plate, and at least one of the plurality of
projections forming a supporting portion disposed at the second
edge for establishing a space of a predetermined width between the
conductive plate portion and the object, and plurality of remaining
projections out of the plurality of projections forming connecting
portions.
14. An electromagnetic shielding plate according to claim 13,
wherein said supporting portion is the same height as the
predetermined width from said conducting covering plate, and a
height of said connecting strips from said conductive covering
plate to said tip portion is higher than a height of said
supporting portion.
15. An electromagnetic shielding plate according to claim 13,
wherein said plate surface of the conductive covering plate has a
portion for bearing load.
16. An electromagnetic shielding structure comprising: an object
including a circuit element mounted thereon; and an electromagnetic
shielding plate for shielding electromagnetic radiation by covering
at least a part of the object; the object comprising a band-shaped
ground pattern surrounding an area on which electromagnetic
shielding is to be provided on a surface where said circuit element
is mounted; wherein the electromagnetic shielding plate comprises a
conductive covering plate having an edge and a plate surface, the
edge and the plate surface lying in transverse planes, a plurality
of spaced-apart notches formed in the conductive covering plate and
defining a plurality of conductive connecting strips, each of the
connecting strips comprising a first portion extending in the plane
of the plate surface and a second portion extending in the plane of
the edge, the second portion terminating in a tip portion that
conducts electromagnetic radiation from the conductive covering
plate to ground of the object, the second portion of each of the
plurality of conductive strips having a tip shape and being
dimensioned to press against the at least part of the object upon
covering the at least part of the object of the conductive covering
plate.
17. An electromagnetic shielding structure according to claim 16,
further comprising a supporting portion for establishing a space
between said electromagnetic shielding plate and said object,
wherein said supporting portion is the same height as the
predetermined width from said electromagnetic shielding plate,
wherein a height of said connecting strips from said
electromagnetic shielding plate to said tip portions is higher than
a height of said supporting portion; and
wherein said supporting portion of said electromagnetic shielding
plate is secured to said object, and said conductive covering and
said object are kept in a positional relationship such that the tip
portion of said connecting strips of said electromagnetic shielding
plate are elastically deformed and are in press contact with said
ground pattern.
18. An electromagnetic shielding structure according to claim 17,
wherein said supporting portion comprises a connecting portion for
connecting said electromagnetic shielding plate with said
object.
19. An electromagnetic shielding structure according to claim 17,
wherein respective gaps between the plurality of said connecting
strips are small than said predetermined width.
20. An electromagnetic shielding structure according to claim 16,
said electromagnetic shielding plate includes a cabinet-fixing
portion for securing a cabinet to said shielding plate.
21. An electromagnetic shielding plate according to claim 16,
wherein said plate surface of the conductive covering plate has a
portion for bearing load.
22. An entertainment system comprising: a main control circuit
substrate including a circuit element mounted thereon; an
electromagnetic shielding plate for shielding electromagnetic
radiation by covering at least a part of the main control circuit
substrate; and an electric power supply unit; the main control
circuit substrate comprising a band-shaped ground pattern enclosing
an area on which electromagnetic shielding is to be provided on a
surface where the circuit element is mounted; wherein the
electromagnetic shielding a plate comprises a conductive covering
plate having an edge and a plate surface, the edge and the plate
surface lying in transverse planes, a plurality of spaced-apart
notches formed in the conductive covering plate and defining a
plurality of conductive connecting strips, each of the connecting
strips comprising a first portion extending in the plane of the
plate surface and a second portion extending in the plane of the
edge, the second portion terminating in a tip portion that conducts
electromagnetic radiation from the conductive covering plate to
ground of the object, the second portion of each of the plurality
of conductive strips having a tip shape and being dimensioned to
press against the at least part of the object upon covering the at
least part of the object of the conductive covering plate.
23. An entertainment system according to claim 22, further
comprising a supporting portion for establishing a space between
said covering plate and said object, wherein said supporting
portion is the same height as the predetermined width from said
covering plate, wherein a height of said connecting strips from
said conductive covering plate to said tip portions is higher than
a height of said supporting portion; and
wherein said supporting portion of said electromagnetic shielding
plate is secured to said main control circuit substrate, and said
electromagnetic shielding plate and said main control circuit
substrate are kept in a positional relationship such that the tip
portion of said connecting strips of said electromagnetic shielding
plate are elastically deformed and are in press contact with said
ground pattern.
24. An entertainment system according to claim 23, wherein the
respective gaps between the plurality of said connecting strips are
smaller than said predetermined width.
25. An electromagnetic shielding plate according to claim 22,
wherein said plate surface of the conductive covering plate has
portion for bearing load.
26. An electromagnetic shielding plate for shielding
electromagnetic radiation by covering at least a part of an object,
the electromagnetic shielding plate comprising: a conductive
covering plate having an edge and a plate surface, the edge and the
plate surface lying in transverse planes; a plurality of
spaced-apart notches formed in the conductive covering plate and
defining a plurality of conductive connecting strips, each of the
connecting strips comprising a first portion extending in the plane
of the plate surface and a second portion extending in the plane of
the edge, the second portion terminating in a tip portion that
conducts electromagnetic radiation from the conductive covering
plate to a ground of the object; the second portion of each of the
plurality of conductive strips having a tip shaped and dimensioned
to press against the at least part of object upon covering the at
least part of object of the conductive covering plate.
27. An electromagnetic shielding plate according to claim 26,
wherein said plate surface of the conductive covering plate has a
portion for bearing load.
28. An electromagnetic shielding plate according to claim 26,
further comprising a supporting portion for establishing a space of
a predetermined width between said conductive covering plate and
said object, and said supporting portion being the same height as
the predetermined width from said conductive covering plate,
wherein a height of said connecting strips from said conductive
covering plate to said tip portions is higher than a height of said
supporting portion.
29. An electromagnetic shielding plate for shielding
electromagnetic radiation by covering at least a part of an object
comprising: a conductive covering plate having an edge and a plate
surface; a plurality of conductive connecting strips provided along
the edge of said covering plate, said connecting strips extending
along said plate surface and downwardly from said edge and
terminating in tip portions that conduct electromagnetic radiation
from said conductive covering plate to a ground of said object;
wherein each of said connecting strips has a front surface and a
back surface in a shape of a plate, and an edge of the front
surface and an edge of the back surface in said tip portion side
are formed in a shape of an arc in approximate point contact with
said ground, said tip portion being adapted to remove flux disposed
on the ground by the point contact.
Description
This invention claims a priority based on Japanese Patent
Application No. 11-257791 filed on Sep. 10, 1999, the entire
contents of which are incorporated herein by reference for all
purposes.
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic shielding
plate, an electromagnetic shielding structure, and an entertainment
system having the electromagnetic shielding structure.
In electronic equipment, there are cases where electromagnetic
waves are generated resulting from actions of internal equipment
and are radiated out to the exterior of equipment. In recent years,
it is strongly desired to minimize radiation of unnecessary
electromagnetic wave in terms of electronic equipment. Therefore,
in electronic equipment, shielding is carried out in such a manner
that the enclosure itself is shielded, or the device mounted
surface of the printed board is shielded by covering it with a
box-shaped member formed of a metal.
For example, in case where the box-shaped member covers the
device-mounted surface of the printed board, the structure will be
as follows. As a first step, a ground pattern is printed on the
circumferential portion on the printed board. On the other hand, an
opening edge of the box-shaped member is turned outwardly to form a
contact surface, which is then placed on the printed board. In this
case, the box is located on the printed board so that the contact
surface of the box comes into contact with the ground pattern
mounted on the circumferential portion of the printed board. In
this situation, the box-shaped member is secured on the printed
board by screwing or some other means.
In such a structure, electromagnetic radiation from the
device-mounted surface to the exterior of the equipment may be
restrained since the device-mounted surface of the printed board is
covered by the box-shaped member.
SUMMARY OF THE INVENTION
The shielding structure described above can ideally restrain
electromagnetic radiation to the exterior of the electromagnetic
equipment. However, in actually, there is a case where restraining
effect for electromagnetic radiation is not exerted satisfactorily.
In other words, product-to-product variations in performance of
electromagnetic radiation are found. According to the analysis
carried out by the inventor of the present invention, it was found
that such variations are caused by insufficient contact between the
contact surface of the box-shaped member and the ground pattern. In
other words, there may be a warp or waviness in the printed board,
thereby generating projections and depressions on the ground
pattern. Since the contact face of the box-shaped member cannot
follow such a warp or waviness, a gap is created between the
contact face and the ground pattern, through which electromagnetic
wave may be radiated. Consequently, sufficient shielding is not
performed.
It is possible to stop up the gap between the contact surface of
the box shaped member and the ground pattern by means of soldering,
whereby the gap may be closed almost completely. As a consequent,
product-to-product variations in shielding performance may be
prevented.
However, in this method, it is necessary to solder all around the
circumference of the printed board. Therefore, "soldering" step is
added to the manufacturing process. The added soldering step has a
problem in that it takes time to carry out. Therefore, it is not
practical to stop up the gap by soldering, except for special
costly products. Therefore, this method is not generally
employed.
Accordingly, the first object of the present invention is to
provide a shielding plate that does not require special mounting
step, is easy to mount, and can prevent radiation of
electromagnetic wave independently of the state of the object to
which it is mounted.
The second object of the present invention is to provide a
shielding structure exhibiting a smaller range of
product-to-product variations in shielding performance, and an
entertainment system that can prevent radiation of electromagnetic
wave by such a shielding structure.
An electromagnetic shielding plate achieving the first object of
the invention is an electromagnetic shielding plate for shielding
electromagnetic wave by covering at least a part of an object
comprising; a covering plate formed of a conductive plate, and a
plurality of connecting strips provided along the edge of the
covering plate, wherein the connecting strip is bent so that the
tip portion thereof projects from the surface of the covering
plate.
The electromagnetic shielding plate for achieving the second object
of the invention comprises an object on which a circuit element is
mounted, an electromagnet shielding plate for shielding
electromagnetic radiation by covering at least a part of the
object, the object including a band-shaped ground pattern
surrounding an area on which electromagnetic shielding is to be
provided on a surface where the circuit element is mounted, the
electromagnetic shielding plate including a covering plate formed
of a conductive plate and a plurality of connecting strips provided
along the edge of the covering plate, the connecting strip being
bent so that the tip portion thereof projects from the surface of
the covering plate, wherein the electromagnetic shielding plate and
the object is kept in a positional relationship wherein the tips of
the connecting strip are brought into press contact with the ground
pattern.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of an electromagnetic shielding plate
according to the first embodiment of the present invention;
FIGS. 2A and 2B are side views of the electromagnetic shielding
plate according to the first embodiment of the present
invention;
FIG. 3 is an explanatory drawing illustrating the positional
relationship between the electromagnetic shielding plate and a
printed board according to the first embodiment of the present
invention;
FIGS. 4A and 4B are enlarged views showing a portion where the leg
portion of the electromagnetic shielding plate and a ground pattern
on a printed board are in contact with respect to each other
according to the first embodiment of the present invention;
FIG. 5 is an explanatory drawing illustrating the positional
relationship between an electromagnet shielding plate and a printed
board according to the second embodiment of the present
invention;
FIGS. 6A and 6B are enlarged views showing a portion where the leg
portion of the electromagnetic shielding plate and a ground pattern
of a printed board are in contact with respect to each other
according to the second embodiment of the present invention;
and
FIG. 7 is a sectional view of an entertainment system having an
electromagnetic shielding plate according to the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, preferred embodiments of the present
invention will now be described. In the following embodiments, an
entertainment system that can be used for playing games, image
reproduction, sound reproduction, and communication is taken as an
example. A shielding plate and a shielding structure of the present
invention are not limited to the entertainment system, but they are
applicable to any other electronic equipment. However, it is
generally preferred that entertainment system is provided at a
relatively low cost. Therefore, the shielding structure of the
present invention is effective when it is applied to the
entertainment system.
The shielding structure according to the embodiment comprises, as
shown in FIG. 3, a printed board 200 to which the shielding is
applied, and an electromagnetic shielding plate 100 (hereinafter
referred to as "shielding plate") for covering the mounting surface
thereof. In the example shown in FIG. 3, the state where the
shielding plate 100 is mounted to one surface of the printed board
200. This invention is not limited to this type of application. For
example, the shielding plates 100 may be mounted on both the
surfaces of the printed plate 200, or the shielding plate 100 may
be mounted on a part of the printed board 200.
As shown in FIG. 3, one of the surfaces of the printed board 200 is
provided with a ground pattern 201 in the shape of a frame. The
ground pattern 201 may be mounted when providing wiring, which is
not shown, on the printed board 200. In this embodiment, the ground
pattern 201 is formed of copper, and provided along the
circumference of the printed board 200. With this, radiation of
electromagnetic wave may be retained in the area all around the
printed board 200. In this embodiment, a part of the ground pattern
201, namely a portion corresponding to the four corners of the
printed board 200 and midway along the length thereof, are provided
with widened areas 203 respectively.
The printed board 200 is provided with through holes 202 for fixing
the shielding plate at a plurality of locations. More specifically,
the widened area 203 of the ground pattern 201 described above are
provided with through holes 202 respectively. Fixing bolts are
passed through these through holes 202 and fixed by nuts. It is
also possible to cut threads on the inner surfaces of these through
holes for engaging bolt with these threads.
Referring now to FIG. 1 and FIG. 2, there are shown a shielding
plate 100 constituting the shielding structure described above.
FIG. 1 is a front view of the shielding plate 100, and FIG. 2A is a
side view showing a part of the shielding plate 100.
The shielding plate 100 is formed of a conductive material having
elasticity. The shielding plate 100 comprises a plate portion 101,
a connecting strip 104, and a supporting portion 105. The
connecting strips 104 are provided at a plurality of locations
along the edge of the plate portion 101. The connecting strip 104
is bent so that the tip portion thereof projects from the plate
portion 101. In other words, this shielding plate 100 is formed in
a box shape comprising a plate portion 101 and a side surface
portion provided around the plate portion 101. The shielding plate
100 is provided with notches 108 extending from the edges of the
side surface portion to a part of the plate portion 101 at a
plurality of locations along the edges of the side surface portion.
The connecting strips 104 are formed by these notches 108. These
notches 108 reach a part of the edge of the plate portion 101,
whereby each connecting strip 104 can be displaced
independently.
The connecting strips 104 are brought into contact with the printed
board 200 at its tip portions 104a as described later. The
supporting portions 105 extend from the edge of the plate portion
101 in the same direction as the connecting strips 104. The
supporting portion 105 includes a foot portion 106 on its tip
portion. The foot portion 106 is composed of a plate that is almost
in parallel with the plate portion 101. The foot portion 106
comprises a through hole 107.
In addition, the plate portion 101 comprises a cabinet fixing
portion 110 for placing the cabinet on the shielding plate 100 and
fixing the cabinet thereto.
FIG. 2B is an enlarged side view showing the shielding plate 100.
Now, assuming that there are an imaginary plane A in which the tip
portions 104a of the connecting strips 104 are aligned and an
imaginary plane B in which the tip of the supporting portions 105
are aligned. The positional relationship between the imaginary
plane A and B is, as clearly be seen from the figure, the imaginary
plane A is located a little outside of the imaginary plane B with
respect to the plate portion 101. In other words, the projecting
length of the connecting strip 104 measured to the tip thereof from
the plate portion 101 is larger than that of the supporting portion
105 from the plate portion 101.
When constructing the shielding structure shown in FIG. 3, the
imaginary plane B is located in the same plane as the surface of
the printed board 200. Since the imaginary plane A is located
outside of the imaginary plane B, the tip portion 104a of the
connecting strip 104 is brought into contact with the ground
pattern 201 without fail. The state of contact at this time is
shown in FIG. 4.
The contact pieces 104 are displaceable independently and exhibit
elasticity. The elasticity ensures that the tip portions 104a and
the ground pattern 201 are brought into press contact with respect
to each other. For example, when the ground pattern 201 has
projections and depressions, the respective connecting pieces 104
are displaced along the projections and depressions of the ground
pattern 201, whereby it ensures that the tip portions 104a are
brought into contact with the ground pattern 201 respectively.
FIG. 4B shows the state where the connecting strips 104 are brought
into press contact with the ground pattern 201. The elasticity of
the connecting strips 104 ensures that the tip 104a of the
connecting strips 104 slightly open outward so as to exhibit warped
shapes. There may be flux in the shape of thin film left on the
ground pattern 201. In such a case, the flux should be scrubbed
away before connecting them electrically. However, as described
above, when the shielding plate 100 of the present invention is
fixed to the printed board 200, the connecting strips 104 open
outward, thus scrubbing residual flux away accordingly. It ensures
the electrical connection between the shielding plate 100 and the
printed board 200. Therefore, it is not necessary to remove the
flux away in advance before the shielding plate 100 of the present
invention is fixed onto the printed board 200. In other words,
contact between the connecting strips 104 and the ground pattern
201 is ensured without removing flux in advance.
When the cabinet, which is not shown, is placed on a cabinet-fixing
portion 110, the shielding plate 100 is applied with a load, which
further ensures contact between the connecting strips 104 and the
ground pattern.
As described thus far, since the respective connecting strips 104
are ensured to be in contact with the ground pattern 201, a high
shielding effect can be obtained.
FIG. 5 and FIG. 6 show a second embodiment of a shielding structure
of the present invention. The shielding structure according to the
present embodiment comprises, as shown in FIG. 5 and FIG. 6,
printed boards 200, 250 (the printed board 250 is not shown in FIG.
5), and a shielding plate 300. In the example shown in FIG. 5 and
FIG. 6, the state where the shielding plate is mounted between two
printed boards is shown.
The shielding plate 300 according to the present embodiment is
formed of a conductive material having resiliency, as is the
shielding plate 100 of the first embodiment. The shielding plate
300 comprises a plate portion 301, connecting strips 302, 303, and
supporting portions 311, 312. The connecting strips 302, 303 are
provided at a plurality of locations along the edge of the plate
portion 301, as in the case of the first embodiment. The plurality
of connecting strips comprises the first connecting strips 301 and
the second connecting strips 303. In other words, the tips of the
first connecting strips 302 are bent toward one surface of the
plate portion 301. The tips of the second connecting strips 303 are
bent toward another surface of the plate portion 301.
The supporting portions 311, 312 are also provided with the first
supporting portion 311 and the second supporting portion 312. On
the tips of the respective supporting portions 311, 312, as in the
first embodiment, there are provided foot portions 313, 314. The
foot portions 313, 314 are provided with the through holes 315,
316. The shielding plate 300 is fixed to the lower printed board
200 in the figure via the through hole 315, and to the upper
printed board 250 in the figure via the through hole 316.
As in the first embodiment, the imaginary plane in which the tips
of the connecting strips 305, 307 are aligned is located outside of
the imaginary plane in which the tips of the supporting portions
311 and 312 are aligned. Therefore, when the printed boards 200 and
250 are fixed on and under the shielding plate 300, the first
connecting strips 302 are brought into press contact with the
ground pattern 201 of the lower printed board 200, and the second
connecting strips 303 are brought into press contact with the
ground pattern 251 of the upper printed board 250 respectively.
FIG. 6 shows how it looks in such a state.
Since the shielding plate 300 serves to enhance the shielding
effect than in the conventional case, even when two printed boards
200 and 250 are disposed one on another, electromagnetic induction
generated between the two printed boards 200 and 250 may be
prevented.
In this embodiment, each connecting strip is bent between its
proximal end 304 and its distal end, so as to be L-shape in cross
section. The overhanging length C from the proximal end 304 of the
first connecting strip 302 to the bent position 305 may be set to
be a different length from the overhanging length D from the
proximal end 304 of the second connecting strip 303 to the bent
position 305. For example, there is a case where it is preferable
to displace the upper printed board 200 from the lower printed
board 250 to an extent for the convenience of arrangement of
substrate. In such a case, the upper printed board 250 may be
displaced from the lower printed board 200 toward the farther side
of the drawing by arranging the strips in such a manner that the
overhanging length C of the first connecting strip 302 on the
nearer side of FIG. 5 is shorter than the overhanging length D of
the second connecting strips 303 on the nearer side, and the
overhanging length C of the first connecting strip 302 on the
farther side of the drawing is longer than the overhanging length D
of the second connecting strip 303 on the farther side.
In the two embodiments described thus far, though the shielding
plate is fixed onto the printed board by providing through holes
onto the shielding plate and the printed board and securing them by
a screw, the fixing method is not limited to this. For example, the
tip of the supporting portion may be provided with a locking
portion for engaging with the printed board to secure them
together, or they may be secured by clips or the like. It is also
possible to secure them by eliminating the supporting portion from
the shielding plate but providing it with through holes only, and
providing the printed board with supporting portions, so that they
are secured together. Alternatively, it is possible to provide the
shielding plate and the printed board with through holes, and
secure them together by means of a member having an internal
thread.
An entertainment system employing a shielding structure will be
explained referring to a figure as the third embodiment of the
present invention. In this embodiment, a structure having a
shielding plate on a part of a surface of the printed board will be
shown as an example.
The entertainment system 500 shown in FIG. 7 comprises at least an
enclosure 505, a main control circuit substrate 510, a shielding
plate 100, a pipe-shaped heat sink 530, a rectangular heat sink
540, a switch inlet unit 550, an electric power supply unit 560,
and a memory card inserting portion 570. The main control circuit
substrate 510 is provided with a circuit element including a
central processing unit 511 mounted thereon. In this entertainment
system 500, the main control circuit substrate 510 that generates
the electronic wave most and the shielding plate 100 constitute the
shielding structure.
A plate portion 121 of the shielding plate 100 is provided with a
through hole 122, through which the rectangular heat sink 540 is
inserted. The rectangular heat sink 540 constitutes a heat
discharging mechanism with the pipe type heat sink 530 to prevent
overheating of the central processing unit 511 in the main control
circuit substrate 510.
The shielding plate 100 is connected to the main control circuit
substrate 510 with the connecting strips 104 in press contact with
the ground pattern to shield electromagnetic waves generated by the
main control circuit substrate 510.
According to the present invention, there is provided the shielding
plate that can be mounted easily without adding any special
mounting steps, and can prevent electromagnetic radiation
independently of the state of the object to which the shielding
plate is mounted.
In addition, according to the present invention, there is provided
a shielding structure having a smaller range of product-to product
variations in shielding performance, and an entertainment system
that can prevent the electromagnetic waves from being radiated by
the use of such a shielding structure.
* * * * *